That looks like a 5V TTL interface. The 5V Tx signal going into the Pi is not good for it, and the 3.3V Tx signal leaving the Pi may not be high enough to register as a logic "1" at the interface.
Try to find a 3.3V TTL interface, or use a level shifter.
Try to find a 3.3V TTL interface, or use a level shifter.
Statistics: Posted by ame — Thu Sep 11, 2025 8:25 pm